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49 lines
1.9 KiB
49 lines
1.9 KiB
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include "table/block_based/index_reader_common.h"
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namespace ROCKSDB_NAMESPACE {
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// Index that leverages an internal hash table to quicken the lookup for a given
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// key.
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class HashIndexReader : public BlockBasedTable::IndexReaderCommon {
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public:
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static Status Create(const BlockBasedTable* table, const ReadOptions& ro,
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FilePrefetchBuffer* prefetch_buffer,
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InternalIterator* meta_index_iter, bool use_cache,
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bool prefetch, bool pin,
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BlockCacheLookupContext* lookup_context,
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std::unique_ptr<IndexReader>* index_reader);
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InternalIteratorBase<IndexValue>* NewIterator(
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const ReadOptions& read_options, bool disable_prefix_seek,
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IndexBlockIter* iter, GetContext* get_context,
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BlockCacheLookupContext* lookup_context) override;
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size_t ApproximateMemoryUsage() const override {
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size_t usage = ApproximateIndexBlockMemoryUsage();
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#ifdef ROCKSDB_MALLOC_USABLE_SIZE
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usage += malloc_usable_size(const_cast<HashIndexReader*>(this));
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#else
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if (prefix_index_) {
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usage += prefix_index_->ApproximateMemoryUsage();
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}
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usage += sizeof(*this);
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#endif // ROCKSDB_MALLOC_USABLE_SIZE
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return usage;
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}
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private:
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HashIndexReader(const BlockBasedTable* t, CachableEntry<Block>&& index_block)
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: IndexReaderCommon(t, std::move(index_block)) {}
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std::unique_ptr<BlockPrefixIndex> prefix_index_;
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};
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} // namespace ROCKSDB_NAMESPACE
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